Inseparable plastic containers can cause great frustration. Containers that are empty stack neatly and take up less room while being stored. The longer containers are stacked inside each other, the greater the chance they will settle and become stuck. The same methods used for separating plastic drinking glasses can be used for larger storage containers.
Place the containers into the bathtub or sink, depending on the size of the containers that are stuck.
Add enough hot tap water to the sink or tub to cover half of the outside container.
Pour ice and cold water into the inside container until the water fills half of the container.
Wait two or three minutes and pull the containers apart. The inside container will have contracted due to the cold, and the outside container will have expanded from the heat. This allows you to separate the containers.
Place the containers in the sink or a grassy area outside.
Lay the containers on one side. Pour vegetable oil around the rim of the bottom container. Rotate the containers while pouring the oil until the four sides have been lubricated.
Allow the oil to seep between the containers and pull the containers apart.
Wash the containers with a mild dishwashing detergent and dry with a cloth.